Multi-rotor Aircrafts Research Articles

Noise attenuation of frequency-modulated multi-rotor using sound field reproduction

Multi-rotor aircraft has great potential in urban traffic and military use and its noise problem has attracted more attention recently. Multi-rotor aircrafts are typically controlled by changing the rotation speeds of the rotors. To reduce the noise of multiple frequency-modulated rotors, a global noise attenuation method is proposed in this study. First, the fast prediction method is used to estimate the global noise of the multirotor with different configurations online. Meanwhile, the sound field reproduction method is used to obtain the control signal of the loudspeaker array to achieve global noise attenuation. Then, the influence of array arrangement on noise reduction is analyzed in the acoustic modal domain, which reveals that different optimization models are needed to minimize the noise power or/and the noise pressure in some directions when the scale of the array is limited. Next, to improve the real-time performance of the system, the online calculation of the optimal control signal is transformed into the offline design of the optimal filter, which satisfies the target frequency-domain characteristics. Finally, the experimental results of the noise of a model quadrotor in the anechoic chamber were consistent with the predicted results. The simulation results of noise attenuation for the quadrotor show that the method proposed reduced the global noise power by about 13 dB. Moreover, the noise region radiated from the quadrotor to the ground with the boundary of 40 dB was reduced to 8.4% of that before control.

Design of a Catapulted Self-deployable UAV

Unmanned Aerial Vehicle (UAV) is playing a gradually enhanced role in fields of recon and information acquisition, however restricted departure condition of fixed wing aircrafts, take-off preparation time of multirotor aircrafts etc. have limited its further applications. This research aims to combine advantage of hovering and self-deployable departure to reconcile the shortcomings, meanwhile adapts to drone swarm trend. A catapulted self-deployable quadrotor is designed using 3D modelling software, and later a compatible self-deployable control algorithm is developed using STM32F103 microcontroller, along with its circuitry. Eventually, a prototype of the design is 3D printed, assembled and tested. This design shows merits of easy to carry, low requirements for take-off conditions and good hovering performance and is compatible for multi-UAVs cooperation tendency.

Design and Experimental Verification of a Multirotor Aircraft with fuzzy neural network controller

Conventional multirotor aircrafts are underactuated, while the translational and rotational motions are strongly coupled. These features severely limit the maneuverability of the aircraft. Therefore, a multi-rotor aircraft is designed, which can perform omnidirectional motion, vector thrust control flight and tilt-hovering. In addition, an fuzzy nerual network controller is designed. And the aircraft demonstrates a higher fault tolerance than the conventional ones. Finally, the experimental results show that the aircraft has a higher maneuverability than the conventional quadrotors.

Obstacle Magnification for 2-D Collision and Occlusion Avoidance of Autonomous Multirotor Aerial Vehicles

Collision or occlusion avoidance is one of the most important functions of autonomous unmanned vehicles when maneuvering or conducting missions, including monitoring or following targets in environments with various obstacles such as trees and buildings. While considering the minimum distance to obstacles or approximating the shape of obstacles is convenient, incorporating the shape of the original obstacles, sometimes, can provide more effective strategies for collision and occlusion avoidance of obstacles with complex shapes or arrangements. This article presents an obstacle magnification algorithm that magnifies but retains the original shape of the detected obstacles. Two simple parameters can adjust the position and magnification of the virtual obstacles. The simulation and outdoor experimental results for the obstacle magnification, implemented on an onboard embedded system, demonstrate the effectiveness of this concept, which should be useful in various applications for small autonomous multirotor aircrafts.

Actuator Fault-Tolerant Control Architecture for Multirotor Vehicles in Presence of Disturbances

In this article we present an actuator fault-tolerant control architecture for the attitude and altitude tracking problem of multirotor aircrafts, under the effects of unknown drag coefficients and external wind. The tracking problem is faced by splitting it into two sub-problems, namely control law and control allocation. The control law is designed in terms of desired forces and moments which should act on the system, it does permit to exploit possible estimations of the disturbances acting on the vehicle and does not depend on the multirotor configuration. The control allocation, instead, optimally solves the redistribution of the control efforts among the motors according to the specific multirotor configuration, moreover it can actively cope with actuator faults whenever their estimations are available. Numerical simulations based on realistic scenarios confirm that the control architecture permits to solve the attitude and altitude tracking problem, despite the effects of faults and disturbances on the system.

Instrumentation and self-repairing control for resilient multi-rotor aircrafts

Purpose Even though multi-rotor aircrafts are becoming more and more prevalent in the fields of aerial photography, agricultural spraying, disaster searching and rescuing, how to achieve higher reliability and robustness of an aircraft still poses a big challenge. It is not a rare case that a multi-rotor aircraft is severely damaged or crushed when an actuator or sensor is malfunctioned. This paper aims at the resilience of an aircraft when a rotor is malfunctioned. Design/methodology/approach The reliability of a multi-rotor aircraft can be measured in terms of stability, robustness, resilience and fault tolerance. All of these four aspects are taken into consideration to improve overall reliability of aircrafts. When a rotor malfunction occurs, the control algorithm is cable of adjusting the operation conditions of the rest of rotors to achieve system stability. Findings In this paper, the authors first present a research topic on the development of a resilient multi-robot aircraft. A multi-rotor aircraft usually possesses more actuated motions than the required degrees of freedom. Originality/value The authors proposed to equip the multi-rotor aircraft with malfunction detecting sensors, and they developed the self-repairing algorithm to re-stabilize the aircraft when a malfunction of a rotor occurs. The design concept and methods were implemented on an eight-rotor aircraft, and the performance of the proposed instrumentation and self-repairing algorithm have been verified and validated.

Modeling of parasitic effects in multi-rotor hybrid aircrafts (Part-II)

Modeling of parasitic effects in multi-rotor hybrid aircrafts (Part-II)

Integration of the Target Position Correction Software with the High Endurance Quadcopter for Search and Rescue Mission

An Unmanned Aerial vehicle (UAV), commonly known as drone, is an aircraft without a human pilot aboard. In recent years, some UAVs are deployed for civil applications, such as policing, firefighting, air pollution monitoring, and aerial search and rescue, etc. Unmanned Aerial vehicle generally include fixed-wing and multi-rotor aircrafts. This research had developed a high endurance quadcopter for search and rescue mission. Target position correction software also was developed in this research. This program uses GPS coordinates embedded in the EXIF information of the aerial photos and more accurately calculates the target’s position. The target’s position error is less than ten meters in 75 meters altitude. Keywords: target position correction software, search and rescue, UAV, quadcopter, and GPS.

Control System Design of a Hex-Rotor Aircraft Based on the Neural Network Sliding Mode Method

For the existing Multi-rotor aircrafts, the under-actuation and strong coupling characteristics have a remarkable influence on their flight performance. In order to overcome this effect, a novel Hex-Rotor aircraft is proposed in this paper. Based on the unique configuration of its six driving rotors, the Hex-Rotor aircraft has the ability to achieve the real independent control on the space 6-DOF channels. An autonomous flight control system with neural network sliding mode is designed. The simulation proved that the novel Hex-Rotor aircraft has desired maneuvering capability,and thehe control system is able to guarantee the aircrafts tracking flight of the aircraft.

Real-Time Implementation of Decoupled Controllers for Multirotor Aircrafts

In this paper, a practical controller design method is presented to control six degrees of freedom multirotor aircrafts---quadrotors. The quadrotor system is divided into four subsystems; that is, the longitudinal, lateral, yaw, and height subsystems. Then, a linear and decoupled nominal model is obtained for each subsystem, whereas coupling and nonlinear dynamics, parametric perturbations, and external disturbances are considered as uncertainties. For each subsystem, a decoupled robust controller is then proposed. Although there exist coupling between each channel, the output tracking errors of the four subsystems are proven to ultimately converge into a-priori set neighborhood of the origin. Finally, real-time implementation results of the decoupled controller are given to demonstrate its viability and applicability.

UAS FOR ARCHAEOLOGY – NEW PERSPECTIVES ON AERIAL DOCUMENTATION

Abstract. In this work some Unmanned Aerial Systems applications are discussed and applied to archaeological sites survey and 3D model reconstructions. Interesting results are shown for three important and different aged sites on north Sardinia (Italy). An easy and simplified procedure has proposed permitting the adoption of multi-rotor aircrafts for daily archaeological survey during excavation and documentation, involving state of art in UAS design, flight control systems, high definition sensor cameras and innovative photogrammetric software tools. Very high quality 3D models results are shown and discussed and how they have been simplified the archaeologist work and decisions.